1. Field of the Invention
The invention relates to a method for manufacturing an ink jet print head which ejects ink from nozzles by applying a pressure to ink contained in ink jet channels.
2. Description of Related Art
An ink jet recording apparatus includes an ink jet print head having multiple nozzles through which ink drops are ejected so as to print characters and diagrams on paper. The ink jet print head includes partition walls that define a plurality of inkjet channels which communicate with the respective nozzles. By applying a drive electric field to the print head to selectively bend the partition walls and change the volume of the ink jet channels, or instantaneously vaporizing the ink so as to generate bubbles, a pressure is applied to the ink contained in the ink jet channels so that the ink is ejected from the channels.
A change in the amount of ink ejected from the ink jet print head causes an increase or decrease in the amount of ink deposited on recording paper, and therefore has a great influence on the quality of resulting images. Conventionally, various ink ejection factors, such as the width and depth of the ink jet channels, which influence ejection of the ink, are respectively controlled to within certain standard ranges, so that the ink can be ejected in a desired ejection state so as to permit printing with a constant amount of ink. Thus, conventional ink jet print heads have been manufactured, while controlling each of the ink ejection factors to be held in its standard range.
In the conventional manufacturing method in which each ejection factor is controlled to within its standard range, however, the normal or desired ejection state or conditions cannot be achieved if even one of the ejection factors deviates from the standard range, thus causing a problem of reduced yield during manufacture of the print heads.
When an actuator substrate of the print head is formed with grooves that provide ink jet channels, for example, the grooves are formed by cutting the actuator substrate by a dicing process using diamond blades. The width of the diamond blades is set to be substantially equal to a given width of the grooves, so that the width and depth of the grooves are controlled to within their standard ranges. However, the width of the diamond blades may be gradually reduced due to wear of the blades during cutting, even if the diamond blades have a considerably high hardness. If such diamond blades are used to continuously cut a large number of actuator substrates, the width of the grooves formed in the actuators finally comes out of or deviates from the standard range. In the conventional manufacturing method in which the ink ejection factors are individually controlled to be within respective standard ranges, the actuators with grooves whose width is outside of the standard range are regarded as defective, and thus will be discarded, resulting in a reduction in the yield during manufacture of the print heads.
It is therefore an object of the invention to provide a method for manufacturing an ink jet print head, wherein an actuator substrate is suitably machined so that ink can be ejected in a desired ejection state to provide desired ink jetting characteristics, even in the case where one or more of a plurality of ejection factors is/are outside of the standard range(s).
To accomplish the above object, the invention provides a method for manufacturing an ink jet print head, wherein a plurality of ejection factors that influence ejection of ink are selected as a combination, and at least one of the ejection factors is controlled so that the ink is ejected in a predetermined ejection state.
In the method as described above, the plurality of ejection factors are combined and at least one of the factors is controlled so as to achieve a desired ink ejection state (ink drop ejection rate and amount of ejected ink drops), and therefore appropriate ranges of the ejection factors can be broadened, as compared with the conventional method where each of the ejection factors is set to within its standard or specified range so as to achieve the desired ejection state. Accordingly, the ink jet print head can be easily machined during its manufacture, irrespective of whether the print head is of an actuator type using a piezoelectric material or a bubble type using bubbles, with a result of an improved yield.
In the manufacturing method as described above, the groove depth and width of the ink grooves may be selected as a combination of the ejection factors, and the groove depth is corrected according to the groove width.
In this case, the ink ejection state or jetting characteristics can be easily controlled by combining the groove depth of the ink grooves that can be easily monitored and controlled, and the groove width.
In the method of the invention as described above, the ink jet print head may be formed with a plurality of ink grooves such that at least one side wall of each of the ink grooves is formed of a piezoelectric material, and a plurality of nozzles that respectively communicate with the ink grooves. In operation, the above-indicated at least one side wall is deformed upon application of a voltage thereto, so that the ink is ejected from each of the ink grooves through a corresponding one of the nozzles. In this manufacturing method, the piezoelectric constant of the piezoelectric material and the groove depth of the ink grooves may be selected as the combination of the ejection factors, and the groove depth may be corrected according to the piezoelectric constant.
In manufacturing the ink jet print head in which the ink is ejected through the nozzles due to changes in the volume of the ink grooves, the ejection state of the ink can be easily controlled by combining the groove depth that can be easily monitored and controlled, and the piezoelectric constant.
In the method of the invention as described above, the ink jet print head may be formed with a plurality of ink grooves such that at least one side wall of each of the ink grooves includes a piezoelectric material and the ink grooves are separated from each other by a plurality of partition walls. The ink jet print head may also be formed with a plurality of nozzles that respectively communicate with the ink grooves. In operation, the above-indicated at least one side wall is deformed upon application of a voltage thereto, so that the ink is ejected from each of the ink grooves through a corresponding nozzle. In this manufacturing method, the width of the partition walls on the opposite sides of each ink groove, and the groove depth of the ink grooves may be selected as the combination of the ejection factors, and the groove depth may be corrected according to the width of the partition walls. In the ink jet print head in which the ink is ejected from the nozzles due to deformation of the ink jet grooves, the ink ejection state can be easily controlled by combining the ink groove depth that can be easily monitored and controlled, and the width of the partition walls.
In the method of the invention as described above, the ink jet print head may be formed with a plurality of ink grooves such that at least one side wall of each of the ink grooves includes a piezoelectric material and the ink grooves are separated from each other by a plurality of partition wall. The ink jet print head may also be formed with a plurality of nozzles that respectively communicate with the ink grooves. In operation, the above-indicated at least one side wall is deformed upon application of a voltage thereto, so that the ink is ejected from each of the ink grooves through a corresponding nozzle. In this manufacturing method, at least two of the groove depth of the ink grooves, groove width of the ink grooves, piezoelectric constant of the piezoelectric material, diameter of the nozzles, and the width of the partition walls on the opposite sides of each ink groove may be selected as the combination of the ejection factors.
In the ink jet print head in which the ink is ejected from the nozzles due to changes in the volume of the ink grooves, the ejection factor which can be most easily controlled can be selected, depending upon manufacturing conditions, from the various kinds of ejection factors.
In the method for manufacturing an ink jet print head as described above, each of the ink grooves may be at least partially defined by a wall formed of a piezoelectric material. In operation, the wall is deformed upon application of a voltage thereto so that the ink is ejected from the print head due to a change in the volume of the ink groove.
In the ink jet print head adapted to eject ink from nozzles by deforming the wall defining each ink groove and changing the volume of the ink groove, appropriate ones of the ejection factors as described above may be selected which include the one which can be easily monitored and controlled, so that the ink ejection state can be easily controlled.